Step 6: Map the results, select which isolates to ribotype.
In the process of isolating bacteria from the watershed, a detailed record of the extent of bacterial contamination in the watershed was created. For example, we collected 390 water samples in the Webhannet watershed over the course of 10 months. Although only 27 of these samples provided bacteria that were genetically analyzed, all of the results were carefully recorded and mapped. See the maps of bacterial contamination here.

Project staff had to determine which samples would be genetically tested. We selected samples that had high concentrations of bacteria and tried create a distribution that covered the entire sampling season, and represented heavily contaminated areas more than clean areas. The table below gives an idea of the selection process. Some samples contained few bacteria and no bacteria were kept from these samples (greyed-out numbers below) Other samples had high bacterial levels, and due to cost constraints we strategically selected a few of these samples for genetic analysis (the yellow numbers below were selected for genetic testing). From each genetically analyzed water sample, ten bacterial colonies were chosen for bacterial testing. For the Webhannet watershed, over 22,000 bacterial colonies were counted, and a carefully selected 159 of these were ribotyped.

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